/*
 * jccoefct.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains the coefficient buffer controller for compression.
 * This controller is the top level of the JPEG compressor proper.
 * The coefficient buffer lies between forward-DCT and entropy encoding steps.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* We use a full-image coefficient buffer when doing Huffman optimization,
 * and also for writing multiple-scan JPEG files.  In all cases, the DCT
 * step is run during the first pass, and subsequent passes need only read
 * the buffered coefficients.
 */
#ifdef ENTROPY_OPT_SUPPORTED
#define FULL_COEF_BUFFER_SUPPORTED
#else
#ifdef C_MULTISCAN_FILES_SUPPORTED
#define FULL_COEF_BUFFER_SUPPORTED
#endif
#endif


/* Private buffer controller object */

typedef struct {
    struct jpeg_c_coef_controller pub;/* public fields */

    JDIMENSION iMCU_row_num;/* iMCU row # within image */
    JDIMENSION mcu_ctr;     /* counts MCUs processed in current row */
    int        MCU_vert_offset; /* counts MCU rows within iMCU row */
    int        MCU_rows_per_iMCU_row; /* number of such rows needed */

    /* For single-pass compression, it's sufficient to buffer just one MCU
     * (although this may prove a bit slow in practice).  We allocate a
     * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each
     * MCU constructed and sent.  (On 80x86, the workspace is FAR even though
     * it's not really very big; this is to keep the module interfaces unchanged
     * when a large coefficient buffer is necessary.)
     * In multi-pass modes, this array points to the current MCU's blocks
     * within the virtual arrays.
     */
    JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];

    /* In multi-pass modes, we need a virtual block array for each component. */
    jvirt_barray_ptr whole_image[MAX_COMPONENTS];
} my_coef_controller;

typedef my_coef_controller * my_coef_ptr;


/* Forward declarations */
METHODDEF boolean compress_data
JPP( ( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) );
#ifdef FULL_COEF_BUFFER_SUPPORTED
METHODDEF boolean compress_first_pass
JPP( ( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) );
METHODDEF boolean compress_output
JPP( ( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) );
#endif


LOCAL void
start_iMCU_row( j_compress_ptr cinfo ) {
/* Reset within-iMCU-row counters for a new row */
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

    /* In an interleaved scan, an MCU row is the same as an iMCU row.
     * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
     * But at the bottom of the image, process only what's left.
     */
    if ( cinfo->comps_in_scan > 1 ) {
        coef->MCU_rows_per_iMCU_row = 1;
    } else {
        if ( coef->iMCU_row_num < ( cinfo->total_iMCU_rows - 1 ) ) {
            coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
        } else {
            coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
        }
    }

    coef->mcu_ctr = 0;
    coef->MCU_vert_offset = 0;
}


/*
 * Initialize for a processing pass.
 */

METHODDEF void
start_pass_coef( j_compress_ptr cinfo, J_BUF_MODE pass_mode ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

    coef->iMCU_row_num = 0;
    start_iMCU_row( cinfo );

    switch ( pass_mode ) {
        case JBUF_PASS_THRU:
            if ( coef->whole_image[0] != NULL ) {
                ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
            }
            coef->pub.compress_data = compress_data;
            break;
#ifdef FULL_COEF_BUFFER_SUPPORTED
        case JBUF_SAVE_AND_PASS:
            if ( coef->whole_image[0] == NULL ) {
                ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
            }
            coef->pub.compress_data = compress_first_pass;
            break;
        case JBUF_CRANK_DEST:
            if ( coef->whole_image[0] == NULL ) {
                ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
            }
            coef->pub.compress_data = compress_output;
            break;
#endif
        default:
            ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
            break;
    }
}


/*
 * Process some data in the single-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the image.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf contains a plane for each component in image.
 * For single pass, this is the same as the components in the scan.
 */

METHODDEF boolean
compress_data( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    JDIMENSION MCU_col_num; /* index of current MCU within row */
    JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
    JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
    int blkn, bi, ci, yindex, yoffset, blockcnt;
    JDIMENSION ypos, xpos;
    jpeg_component_info * compptr;

    /* Loop to write as much as one whole iMCU row */
    for ( yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
          yoffset++ ) {
        for ( MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col;
              MCU_col_num++ ) {
            /* Determine where data comes from in input_buf and do the DCT thing.
             * Each call on forward_DCT processes a horizontal row of DCT blocks
             * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks
             * sequentially.  Dummy blocks at the right or bottom edge are filled in
             * specially.  The data in them does not matter for image reconstruction,
             * so we fill them with values that will encode to the smallest amount of
             * data, viz: all zeroes in the AC entries, DC entries equal to previous
             * block's DC value.  (Thanks to Thomas Kinsman for this idea.)
             */
            blkn = 0;
            for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
                compptr = cinfo->cur_comp_info[ci];
                blockcnt = ( MCU_col_num < last_MCU_col ) ? compptr->MCU_width
                           : compptr->last_col_width;
                xpos = MCU_col_num * compptr->MCU_sample_width;
                ypos = yoffset * DCTSIZE;/* ypos == (yoffset+yindex) * DCTSIZE */
                for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) {
                    if ( ( coef->iMCU_row_num < last_iMCU_row ) ||
                        ( yoffset + yindex < compptr->last_row_height ) ) {
                        ( *cinfo->fdct->forward_DCT )( cinfo, compptr,
                                                       input_buf[ci], coef->MCU_buffer[blkn],
                                                       ypos, xpos, (JDIMENSION) blockcnt );
                        if ( blockcnt < compptr->MCU_width ) {
                            /* Create some dummy blocks at the right edge of the image. */
                            jzero_far( (void FAR *) coef->MCU_buffer[blkn + blockcnt],
                                      ( compptr->MCU_width - blockcnt ) * SIZEOF( JBLOCK ) );
                            for ( bi = blockcnt; bi < compptr->MCU_width; bi++ ) {
                                coef->MCU_buffer[blkn + bi][0][0] = coef->MCU_buffer[blkn + bi - 1][0][0];
                            }
                        }
                    } else {
                        /* Create a row of dummy blocks at the bottom of the image. */
                        jzero_far( (void FAR *) coef->MCU_buffer[blkn],
                                  compptr->MCU_width * SIZEOF( JBLOCK ) );
                        for ( bi = 0; bi < compptr->MCU_width; bi++ ) {
                            coef->MCU_buffer[blkn + bi][0][0] = coef->MCU_buffer[blkn - 1][0][0];
                        }
                    }
                    blkn += compptr->MCU_width;
                    ypos += DCTSIZE;
                }
            }
            /* Try to write the MCU.  In event of a suspension failure, we will
             * re-DCT the MCU on restart (a bit inefficient, could be fixed...)
             */
            if ( !( *cinfo->entropy->encode_mcu )( cinfo, coef->MCU_buffer ) ) {
                /* Suspension forced; update state counters and exit */
                coef->MCU_vert_offset = yoffset;
                coef->mcu_ctr = MCU_col_num;
                return FALSE;
            }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef->mcu_ctr = 0;
    }
    /* Completed the iMCU row, advance counters for next one */
    coef->iMCU_row_num++;
    start_iMCU_row( cinfo );
    return TRUE;
}


#ifdef FULL_COEF_BUFFER_SUPPORTED

/*
 * Process some data in the first pass of a multi-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the image.
 * This amount of data is read from the source buffer, DCT'd and quantized,
 * and saved into the virtual arrays.  We also generate suitable dummy blocks
 * as needed at the right and lower edges.  (The dummy blocks are constructed
 * in the virtual arrays, which have been padded appropriately.)  This makes
 * it possible for subsequent passes not to worry about real vs. dummy blocks.
 *
 * We must also emit the data to the entropy encoder.  This is conveniently
 * done by calling compress_output() after we've loaded the current strip
 * of the virtual arrays.
 *
 * NB: input_buf contains a plane for each component in image.  All
 * components are DCT'd and loaded into the virtual arrays in this pass.
 * However, it may be that only a subset of the components are emitted to
 * the entropy encoder during this first pass; be careful about looking
 * at the scan-dependent variables (MCU dimensions, etc).
 */

METHODDEF boolean
compress_first_pass( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
    JDIMENSION blocks_across, MCUs_across, MCUindex;
    int bi, ci, h_samp_factor, block_row, block_rows, ndummy;
    JCOEF lastDC;
    jpeg_component_info * compptr;
    JBLOCKARRAY buffer;
    JBLOCKROW thisblockrow, lastblockrow;

    for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
          ci++, compptr++ ) {
        /* Align the virtual buffer for this component. */
        buffer = ( *cinfo->mem->access_virt_barray )
                 ( (j_common_ptr) cinfo, coef->whole_image[ci],
                  coef->iMCU_row_num * compptr->v_samp_factor,
                  (JDIMENSION) compptr->v_samp_factor, TRUE );
        /* Count non-dummy DCT block rows in this iMCU row. */
        if ( coef->iMCU_row_num < last_iMCU_row ) {
            block_rows = compptr->v_samp_factor;
        } else {
            /* NB: can't use last_row_height here, since may not be set! */
            block_rows = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
            if ( block_rows == 0 ) {
                block_rows = compptr->v_samp_factor;
            }
        }
        blocks_across = compptr->width_in_blocks;
        h_samp_factor = compptr->h_samp_factor;
        /* Count number of dummy blocks to be added at the right margin. */
        ndummy = (int) ( blocks_across % h_samp_factor );
        if ( ndummy > 0 ) {
            ndummy = h_samp_factor - ndummy;
        }
        /* Perform DCT for all non-dummy blocks in this iMCU row.  Each call
         * on forward_DCT processes a complete horizontal row of DCT blocks.
         */
        for ( block_row = 0; block_row < block_rows; block_row++ ) {
            thisblockrow = buffer[block_row];
            ( *cinfo->fdct->forward_DCT )( cinfo, compptr,
                                           input_buf[ci], thisblockrow,
                                           (JDIMENSION) ( block_row * DCTSIZE ),
                                           (JDIMENSION) 0, blocks_across );
            if ( ndummy > 0 ) {
                /* Create dummy blocks at the right edge of the image. */
                thisblockrow += blocks_across;/* => first dummy block */
                jzero_far( (void FAR *) thisblockrow, ndummy * SIZEOF( JBLOCK ) );
                lastDC = thisblockrow[-1][0];
                for ( bi = 0; bi < ndummy; bi++ ) {
                    thisblockrow[bi][0] = lastDC;
                }
            }
        }
        /* If at end of image, create dummy block rows as needed.
         * The tricky part here is that within each MCU, we want the DC values
         * of the dummy blocks to match the last real block's DC value.
         * This squeezes a few more bytes out of the resulting file...
         */
        if ( coef->iMCU_row_num == last_iMCU_row ) {
            blocks_across += ndummy;/* include lower right corner */
            MCUs_across = blocks_across / h_samp_factor;
            for ( block_row = block_rows; block_row < compptr->v_samp_factor;
                  block_row++ ) {
                thisblockrow = buffer[block_row];
                lastblockrow = buffer[block_row - 1];
                jzero_far( (void FAR *) thisblockrow,
                          (size_t) ( blocks_across * SIZEOF( JBLOCK ) ) );
                for ( MCUindex = 0; MCUindex < MCUs_across; MCUindex++ ) {
                    lastDC = lastblockrow[h_samp_factor - 1][0];
                    for ( bi = 0; bi < h_samp_factor; bi++ ) {
                        thisblockrow[bi][0] = lastDC;
                    }
                    thisblockrow += h_samp_factor;/* advance to next MCU in row */
                    lastblockrow += h_samp_factor;
                }
            }
        }
    }
    /* NB: compress_output will increment iMCU_row_num if successful.
     * A suspension return will result in redoing all the work above next time.
     */

    /* Emit data to the entropy encoder, sharing code with subsequent passes */
    return compress_output( cinfo, input_buf );
}


/*
 * Process some data in subsequent passes of a multi-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the scan.
 * The data is obtained from the virtual arrays and fed to the entropy coder.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf is ignored; it is likely to be a NULL pointer.
 */

METHODDEF boolean
compress_output( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) {
    my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
    JDIMENSION MCU_col_num; /* index of current MCU within row */
    int blkn, ci, xindex, yindex, yoffset;
    JDIMENSION start_col;
    JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
    JBLOCKROW buffer_ptr;
    jpeg_component_info * compptr;

    /* Align the virtual buffers for the components used in this scan.
     * NB: during first pass, this is safe only because the buffers will
     * already be aligned properly, so jmemmgr.c won't need to do any I/O.
     */
    for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
        compptr = cinfo->cur_comp_info[ci];
        buffer[ci] = ( *cinfo->mem->access_virt_barray )
                     ( (j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
                      coef->iMCU_row_num * compptr->v_samp_factor,
                      (JDIMENSION) compptr->v_samp_factor, FALSE );
    }

    /* Loop to process one whole iMCU row */
    for ( yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
          yoffset++ ) {
        for ( MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
              MCU_col_num++ ) {
            /* Construct list of pointers to DCT blocks belonging to this MCU */
            blkn = 0;   /* index of current DCT block within MCU */
            for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
                compptr = cinfo->cur_comp_info[ci];
                start_col = MCU_col_num * compptr->MCU_width;
                for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) {
                    buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
                    for ( xindex = 0; xindex < compptr->MCU_width; xindex++ ) {
                        coef->MCU_buffer[blkn++] = buffer_ptr++;
                    }
                }
            }
            /* Try to write the MCU. */
            if ( !( *cinfo->entropy->encode_mcu )( cinfo, coef->MCU_buffer ) ) {
                /* Suspension forced; update state counters and exit */
                coef->MCU_vert_offset = yoffset;
                coef->mcu_ctr = MCU_col_num;
                return FALSE;
            }
        }
        /* Completed an MCU row, but perhaps not an iMCU row */
        coef->mcu_ctr = 0;
    }
    /* Completed the iMCU row, advance counters for next one */
    coef->iMCU_row_num++;
    start_iMCU_row( cinfo );
    return TRUE;
}

#endif /* FULL_COEF_BUFFER_SUPPORTED */


/*
 * Initialize coefficient buffer controller.
 */

GLOBAL void
jinit_c_coef_controller( j_compress_ptr cinfo, boolean need_full_buffer ) {
    my_coef_ptr coef;

    coef = (my_coef_ptr)
           ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                        SIZEOF( my_coef_controller ) );
    cinfo->coef = (struct jpeg_c_coef_controller *) coef;
    coef->pub.start_pass = start_pass_coef;

    /* Create the coefficient buffer. */
    if ( need_full_buffer ) {
#ifdef FULL_COEF_BUFFER_SUPPORTED
        /* Allocate a full-image virtual array for each component, */
        /* padded to a multiple of samp_factor DCT blocks in each direction. */
        int ci;
        jpeg_component_info * compptr;

        for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
              ci++, compptr++ ) {
            coef->whole_image[ci] = ( *cinfo->mem->request_virt_barray )
                                    ( (j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
                                     (JDIMENSION) jround_up( (long) compptr->width_in_blocks,
                                                            (long) compptr->h_samp_factor ),
                                     (JDIMENSION) jround_up( (long) compptr->height_in_blocks,
                                                            (long) compptr->v_samp_factor ),
                                     (JDIMENSION) compptr->v_samp_factor );
        }
#else
        ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
#endif
    } else {
        /* We only need a single-MCU buffer. */
        JBLOCKROW buffer;
        int i;

        buffer = (JBLOCKROW)
                 ( *cinfo->mem->alloc_large )( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                              C_MAX_BLOCKS_IN_MCU * SIZEOF( JBLOCK ) );
        for ( i = 0; i < C_MAX_BLOCKS_IN_MCU; i++ ) {
            coef->MCU_buffer[i] = buffer + i;
        }
        coef->whole_image[0] = NULL;/* flag for no virtual arrays */
    }
}
